Does POA-Annua also germinate in the spring?

Kentucky bluegrass, Fescue, Rye and Bent, etc
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northeastlawn
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Does POA-Annua also germinate in the spring?

Post by northeastlawn » July 6th, 2020, 5:10 pm

I am having an odd year this year in my KBG lawn. Last year I put a Promadime pre-m down in August and late Sept. I also put down a pre-m for crab grass in April. In spring I got tons of KBG seedheads. More than I ever have, it made it hard to really spot the POA-Annua, but pulled a ton of it out when it was small in April.

My bare spots stayed bare for well into June; and I could see the little KBG rhizomes spreading into them, the lawn spread really great this year. It left me thinking that between the pre-m and hand pulling the lawn was POA Annua free.

But the last 2-3 weeks, the KBG seedheads died off and I have an explosion in POA Annua. A lot of the POA Annua it is going brown and already dining off, but I just can't figure out where it came from all of a sudden.

Is it possible my spring pre-m wore off and some time in May or June the POA-Annua germinated?

There was cool nights it could have happened.

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ken-n-nancy
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Re: Does POA-Annua also germinate in the spring?

Post by ken-n-nancy » July 6th, 2020, 6:28 pm

The short answer is that it sure seems to me that Poa annua germination completely ignores the calendar and simply germinates any time that conditions are right.

If conditions are good in April, Poa annua seeds germinate.

If conditions are good in June, Poa annua germinates then.

If conditions are still good in November, Poa annua germinates then, too.

If you get a warm spell in February, Poa annua germinates then.

Given that Poa annua survives everywhere, listed in the invasive weeds list in such wide ranging locations as Denali National Park (Alaska), Antarctica, Death Valley National Park (California), Hawaii Volcanoes National Park, the Sonoran Desert (Arizona), and basically every climate in between, I don't think there's any location or season that is "safe" from Poa annua germination and establishment! If the conditions are right for just a couple weeks, Poa annua will germinate and grow, regardless of what the calendar says. It is a prolific seeder, so once it has grown somewhere and gone to seed, there will be seeds in the soil for years after it seeded.

All I can say is that if one keeps a pre-emergent down for as much of the year as one can manage, pulls or otherwise controls every Poa annua plant you see, and remains diligent in both of these, there will be less and less Poa annua germinating in your lawn each year. However, if you let it go to seed again (which happens fast!) then it will seize the opportunity...

northeastlawn
Posts: 1259
Joined: June 1st, 2015, 3:10 pm
Location: S.E. Mass.
Grass Type: KBG
Lawn Size: 1000-3000
Level: Experienced

Re: Does POA-Annua also germinate in the spring?

Post by northeastlawn » July 6th, 2020, 7:38 pm

That actually makes sense as in previous years, I was pulling huge clumps of POA-A out of the problem areas. Last summer I really stretched the watering and toasted my KBG, but the POA-A really got hit hard, but I noticed as soon as September came around the POA-A started coming back from dead looking plants I could tell from the seedheads.

In the Fall I was hand pulling POA-A that was coming back and it was still coming up in largish type plants. The stuff I am pulling now is on the smaller side and Junes early heat wave made a lot of it turn brown already. So this must be this years crop that the pre-m didnt work on or germinated outside of when it was effective.

Next year my new strategy may be Dimension for crab grass in the early spring and then try to use Prodiamine in May, August, and September.

But then again I have to get through this summer first.

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